The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
권호 표지
DOI QR코드

DOI QR Code

Simulation of Temporal Variation of Acoustic Transmission Loss by Internal Tide in the Southern Sea of Jeju Island in Summer

여름철 제주 남부해역에서 내부 조석에 의한 음파 전달손실의 시간적 변화 모의실험

  • Kim, Juho (Department of Ocean System Engineering, College of Ocean Science, Jeju National University) ;
  • Kim, Hansoo (Department of Ocean System Engineering, College of Ocean Science, Jeju National University) ;
  • Paeng, Dong-Guk (Department of Ocean System Engineering, College of Ocean Science, Jeju National University) ;
  • Pang, Ig-Chan
  • 김주호 (제주대학교 해양시스템공학과) ;
  • 김한수 (제주대학교 해양시스템공학과) ;
  • 팽동국 (제주대학교 해양시스템공학과) ;
  • 방익찬 (제주대학교 지구해양과학과)
  • Received : 2014.08.04
  • Accepted : 2014.12.01
  • Published : 2015.01.31
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, temporal variations of acoustic transmission loss (TL) affected by internal tide are studied by computer simulation using oceanic data measured in the southern sea of Jeju Island in summer. Temperature was measured with depth (bottom depth are nearly 80 m) in two sites near Seogwipo coast every one hour for 25 hours during July 27 and 28, 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10 m. In order to investigate temporal variation of TL by internal tide, acoustic propagation between two measurement sites (3.8 km distance) was simulated with a source depth of 10 m. TL variation for 1/3 octave band of 100 Hz center frequency highly coincided with tidal period but more complex variation with indistinct tidal period was observed for 1 kHz. Maximun standard deviation of TL variation was 4.2 dB for 100 Hz at 2.8 km distance from a source and it was 3.7 dB for 1 kHz. The tidal variation was also shown in detection range and its maximum variance was less than 1 km. These results imply that temporal variation of TL should be considered for acoustic researches at the southern sea of Jeju Island.

여름철 제주 남부해역에서 내부조석에 의한 음향특성 변화를 실측 자료와 모의실험을 통해 연구하였다. 이를위해 서귀포 인근 해역의 수심 80 m 내외인 두 정점에서 2009년 7월 27일과 28일에 걸쳐 25시간동안 한 시간 간격으로 수심별 수온을 측정하였다. 그 결과 조석에 의해 해수 상층부의 등수온선이 약 10 m이상 반일주기로 변하는 현상이 관측되었다. 이로 인한 음파전달손실의 시간적 변화를 확인하기 위해 음원을 수심 10 m에 두고 거리 3.8 km 떨어진 두 관측 정점 사이에서 음파전달을 모의하였다. 중심주파수 100 Hz인 1/3 옥타브 밴드의 경우 특정 수심 및 거리에서 반일주기가 지배적 이었으나 1 kHz의 경우는 반일주기 성분이 거의 나타나지 않고 복잡한 변화를 보였다. 음원에서 거리 2.8 km떨어진 지점에서 시간에 따른 전달손실 변화의 표준편차는 중심주파수 100 Hz의 경우 수심에 따라 최대 4.2 dB 였으며, 1 kHz의 경우 최대 3.7 dB인 것으로 나타났다. 탐지성능 60 dB를 고려한 탐지거리를 분석한 결과 두 중심주파수 경우 모두 반일주기 변화가 나타났으며 최대 1.0 km 미만의 변화를 나타냈다. 이러한 결과는 차후 제주 남부해역의 음향 특성 실험 및 연구 수행 시 전달손실의 시변동성에 대해 고려할 필요가 있음을 시사한다.

Keywords

References

  1. C. K. Kim, K. I. Chang, K. Park, and M. S. Suk, "The south sea circulation of korea: Two-dimensional barotrophic model" (in Korean), J. Kr. Soc. Oceanogr. 5, 257-226 (2000).
  2. H. J. Lee, H. J. Lee, J. H. Park, and H. K. Ha, "Seasonal variability of internal tides around the korea strait: 3-D high-resolution model simulation" (in Korean), Ocean and Polar Res. 36, 1-12 (2014). https://doi.org/10.4217/OPR.2014.36.1.001
  3. J. H. Moon, I. C. Pang, and J. H. Yoon, "Response of the Changjiang diluted water around Jeju Island to external forcings: A modeling study of 2002 and 2006," Cont. Shelf Res. 29, 1549-1564 (2009). https://doi.org/10.1016/j.csr.2009.04.007
  4. O. Jeong, H. Lee, I. C. Pang, and J. S. Lee, "The characteristics of tide and tidal current around the Jeje-do" (in Korean), Proc. Kr. Soc. Coastal Ocean Eng. 17, 80-83 (2008). https://doi.org/10.9765/KSCOE.2011.23.5.393
  5. K. H. Oh, Y. G. Park, D. I. Lim, H. S. Jung, and J. S. Shin, "Characteristics of temperature and salinity observed at the Ieodo ocean research station" (in Korean), J. Mar. Env. Eng. Soc. Kr. 9, 225-234 (2006).
  6. B. N. Kim, B. K. Choi, B. C. Kim, S. K. Jung, Y. Park, and Y. K. Lee, "Seawater temperature and wind speeds dependences and diurnal variation of ambient noise at the snapping shrimp colony," OCEANS 2012, Yeosu, 1-3, (2012).
  7. P. Abbot, S. Seluzza, I. Dyer, B. Gomes, J. Fulford, and J. Lynch, "Effects of east china sea shallow-water environment on acoustic propagation," IEEE J. Ocean. Eng. 28, 192-211 (2003). https://doi.org/10.1109/JOE.2003.811901
  8. S. Finette, T. Evans and C. Shen, "Submesoscale modeling of environmental variability in a shelf-slope region and the effect on acoustic fluctuations," in Impact of Littoral Environmental Variability of Acoustic Predictions and Sonar Performance, edited by N. G. Pace, F. B. Jensen (Springer, Netherlands, 2002), pp. 401-408.
  9. S. Finette, R. Oba, C. Shen, and T. Evans, "Acoustic propagation under tidally driven, stratified flow," J. Acoust. Soc. Am. 121, 2575-2590 (2007). https://doi.org/10.1121/1.2713724
  10. F. P. Lermusiaux, J. Xu, C. F. Chen, S. Jan, L. Y. Chiu, and Y. J. Yang, "Coupled ocean-acoustic prediction of transmission loss in a continental shelfbreak region: predictive skill, uncertainty quantification, and dynamical sensitivities," IEEE J. Ocean. Eng. 35, 895-916 (2010). https://doi.org/10.1109/JOE.2010.2068611
  11. J. Xu, F. L. Pierre, J. H. Patrick, W. G. Leslie, and O. G. Logutov, "Spatial and temporal variations in acoustic propagation during the PLUSNet'07 exercise in Dabob Bay," POMA 4, 175-187 (2008).
  12. J. Yang, D. Rousff, D. Tang, and S. H. Frank, "Effect of the internal tide on acoustic transmission loss at midfrequencies," IEEE J. Ocean. Eng. 35, 3-11 (2010). https://doi.org/10.1109/JOE.2009.2038984
  13. Predicted sea level of July 2009 (in Korean) "http://www.jeju.go.kr/contents/depart.php?depart=&silkuk=32& mid=08".
  14. Y. Kitade and M. Matsuyama, "Characteristics of Internal Tides in the Upper Layer of Sagami Bay," J. Oceanogr. 53, 143-159 (1997).
  15. E. L. Hamilton, "Geoacoustic modeling of the sea floor," J. Acoust. Soc. Am. 68, 1313-1340 (1980). https://doi.org/10.1121/1.385100
  16. J. S. Youn and G. W. Go, "Sedimentological characteristics of the surface sediment in the southern see off cheju island, Korea" (in Korean), J. Oceanogr. Soc. Kr. 22, 130-142 (1987).
  17. M. D. Collins, "User's Guide for RAM Versions 1.0 and 1.0 p," Naval Research Lab, Washington, DC 20375 (1995).
  18. J. Youn and T. Kim, "Geochemical composition and provenance of surface sediments in the western part of Jeju Island, Korea" (in Korean), J. Kr. Earth Sci. Soc. 29, 328-340 (2008). https://doi.org/10.5467/JKESS.2008.29.4.328
  19. B. N. Kim, B. K. Choi, S. H. Kim, B. C. Kim, S. K. Jung, and Y. K. Lee, "Effect of underwater sound channel on variation of ambient noise level in eastern sea of Korea," Japanese J. App. Phys. 53, 07KG04 (2014).